Mistakes happen, right? Every once in a while, your client's installer makes one, despite the fact that you have designed everything correctly. For instance, occasionally plumbers inadvertently reverse the water supply lines (that is, when the hot water supply comes from the right, instead of from the left, and when the cold water supply comes from the left, instead of the right.) What if this happens with the new GrohFlex? Luckily, there is no reason to tear down the expensive Italian tile, change out the piping, or any other drastic measures. The solution depends on which bathroom trim kit you've paired with the GrohFlex rough-in.

Pressure Balance Cartridge: If the trim kit cartridge is pressure balance, the plumber can simply turn the cartridge over.

Thermostatic Cartridge: The solution is slightly more expensive for the thermostat specification, but not nearly as costly as changing the pipes, and so much simpler. All the plumber needs to do is purchase a reverse cartridge (available now from Grohe), and everything will be fixed. (Part Number 47175000.)

Apply what you learned: John, your client's plumber, calls you in a panic: "I think I accidentally reversed the water lines on that new GrohFlex valve, but the wall has already been closed. What do I do now?" "No need to panic, John," you reassure him. "There is an easy solution!" You check the invoice and see that you sold a 35026000 with a 19849000. How would you respond to John the plumber?